login
A294052
Number of set partitions of [n] such that the maximal absolute difference between consecutive elements within a block equals three.
2
2, 13, 61, 248, 935, 3368, 11777, 40347, 136214, 454922, 1507000, 4961100, 16253188, 53045703, 172607505, 560317916, 1815445901, 5873136282, 18976870985, 61256217631, 197573796328, 636837047532, 2051636248268, 6606758265032, 21268025275930, 68445465415825
OFFSET
4,1
FORMULA
G.f.: (x-2)*x^4/((x-1)*(x^2-3*x+1)*(x^3-x^2-3*x+1)).
a(n) = A287275(n) - A001519(n).
MATHEMATICA
LinearRecurrence[{7, -15, 8, 5, -5, 1}, {2, 13, 61, 248, 935, 3368}, 30] (* Harvey P. Dale, Nov 22 2023 *)
CROSSREFS
Column k=3 of A287213.
Sequence in context: A290721 A354942 A205532 * A353177 A089130 A081340
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Oct 22 2017
STATUS
approved